Amplifying apparatus



Feb. 35, E g 5 THOMPSON 1,7911%35 AMPLIFYING APPARATUS Filed Dec. 24. 1927 Invent or: Browdefi J. Thompson by M Hus Attorney Patented Feb. 3, 1931 UNITED STATES PATENT orrics naowinisa J. THOMPSON, or SCHENEOTADY, NEW YORK, ASSIGNOR ro GENERAL ELEC- rmc GOMIANY, A CORPORATION or NEW YORK ArarLIrYrNe APPARATUS Application filed December 24, 1927. Serial No. 242,475.

My present invention relatesto amplifying apparatus, and more particularly to circuit arrangements employed with electron dis charge devices to obtain regenerative amplification with high frequency currents.

In the usual forms of regenerative circuit connections which are employed with electron discharge apparatus for obtaining a high degree of amplification it is known that if the apparatus is to be used to amplify a wide range of frequency the regenerative connections must be varied from time to time as the frequency'to be amplified varies in order best results. If the regenerative connection is adjusted to. give the maximum degree of amplification without oscillations atthe higher frequencies to be amplified then at the lower frequencies the degree of amplification obtained will be much less and adjustment must be made in order to obtain sat isfactory results.

- The object of my invention is to overcome this disadvantage and providean amplifying 'mentalitles it is possible to system in which regenerative amplification is usefully employed and in which the degree of amplification which may be obtained will be substantially the same throughout the range of frequencies for which the system is intended to operate without any necessity for adjusting the regenerative connections as the frequency is varied. To accomplish this result I provide two separate means for producing regenerative amplication, oneof which is most efi'ective at the higher frequencies and the other of which is most efiective at the lower frequencies. By the proper initial'adj ustment of these instruobtain a substantially uniform degree of amplification throughout the range of frequencies over which the system is designed to operate. v

The novel features which I believe to be characteristic of my invention are setforth zation whereby my invention may be carried into effect.

I have indicated in the drawing an electron discharge device 1 of the four-electrode type having an electron emittingcathode 2, an anode 3 and two grids 4 and 5. This device may be constructed in any desired way so that the electron stream in flowing from the cathode tothe anode 3 passes successively the two grids 4 and 5. The grid 4 is connected to a portion of the battery 6 so that it has impressed thereon a suitable positive potential with reference to to. operate efiiciently as a space charge grid. The grid 5 is employed in the usual manner to control the electron stream through the device. In the present case I have indicated a tuned input circuit 7 with a grid condenser 8, and grid leak 9, whereby;v the device may operate as a detector of high frequency currents impressedupon it from the antenna 10. The output circuit of the device includes all of the battery 6, the tickler or feedback coil 12 which is inductively coupled to the input circuit so as to provide a feed-back of energy for the purpose of giving regenerative amplification.

I have also provided in the circuit of the the cathode to enable it telephone receivers 11 and a space charge grid 4 an impedance rload conin potential of the plate or anode. By rea-- son of the'capacity between the two grids a feed-back action may be produced between the two grids which will affect the potential of the control grid 5 and thereby modify the amplifying action of the device. In order that this potential fed back through the capacity between the grids may assist in producing amplification the. reactance of the space charge grid circuit must be capacitive, therefore, as above stated, I adjust the v space charge grid so that it has a suificient.

. capacitive'reactance becomes less and there-- fore the potential changes of the space charge grid become less.

The feed-back coil l2 on the other hand is adjusted so as to give the maximum degree of amplification desired at the highest frequency which the system is intended to amplify. If it remains fixed atthis point the regenerative amplification due to the feedback coil will decrease as the fre uency applied to the system decreases. T usit will be seen that the two means provided for producing amplification vary in opposite directlons as the .frequency varies. As a result it is possible by the joint action of the two means to obtain a substantially uniform degree of regenerative amplification over the entire range of frequencies at which the apparatus is designed to operate.

While I have shown and described the preferred embodiment of m invention it will of course be understood that many mod ifications in the circuit arrangement employed as well as in the specific form of apparatus used, may be made without departing from the scope of my invention as set forth in the appended claims.

What I claimas new and desire 'to secure 7 1 by Letters Patent of the United States is:

1. The combination with an" electron discharge device having an electron emitting cathode and anode and two grids which are successively passed by ,the electron stream of separate circuits connecting the cathode with each of the other electrodes, and two separate means for producing regenerative amplification by the action of one of said grids, one of said means. being most effective at the higher frequencies and other means being most effective at the lower frequencies at which the circuits are intended to operate.

2.'The combination with an electron discharge device having an electron emitting cathode and anode and two grids which are successively passed by the electron stream, of separate circuits connecting the cathode with each of the other electrodes, and an inductive feedback from the anode circuit to the circuit of one grid and a capacitive feed back from the other grid to the first grid.

3. The, combination with an electron discharge device having an electron emitting cathode and anodeand two grids which are successively passed by the electron stream, of separate circuits connectin the cathode with each of the other. elect es, means for impressing high frequency oscillations on the 4. The combination with an electron discharge device having an electron emitting cathode and anode and two grids which are successively passed by the electron stream, of separate, circuits connectin the cathode with each of the other electro es, means for impressing high frequency oscillations on the circuit ofone grid, an inductive feed back connection from the anode circuit to id cir- "cuit upon which high frequency oscillations are impressed, and means for producing a capacitive reactance on the circuit of the other grid.

' 5. The combination with an electron discharge device having an electron emitting cathode and anode and two grids which are successively passed by the electron stream, of separate circuits connecting the cathode with each of the other electrodes, and two separate means for producin regenerative amplification by the action of the grid nearest the anode, one of said means being most effective at the higherfrequenci'es and the other means being most effective at the lower frequencies at which the circuits are intended to operate. 1

6. The combination with an electron discharge device having an electron emitting cathode and anode and two grids which are successively passed bythe electron stream, of separate circuits connecting the cathode with each of the other electrodes and an in ductive feed back from the anode circuit to the circuit of the grid nearest the anode, and

a capacitive feed back from the other grid to to the grid circuit upon which oscillations are impressed, and a second feedback to that grid circuit from the other grid.

8. The combination with an electron dis-.

charge device having an electron emitting cathode and anode and two grids which are successively passed by the electron stream, of separate circuits connecting the cathode with each of the other electrodes, means for impressing high frequency oscillations on the circuit of the grid nearest the anode, an inductive feedback connection from the anode I circuit to the grid circuit upon which high frequency oscillations are impressed, and g a means for producinga capacitive reactanc in the circuit of the other grid.

9. The combination with an electron discharge device having an electron emitting 1 cathode and anode and two glrids which are successively passed by the e ectron stream,

of separate circuits connectin the cathode with each of the other electro es, meansior impressing high frequency osci1lations-on the circuit of the grid nearest the anode, a fixed inductive feed back connection from the anode circuit to the id circuit upon which high frequency 050' lations are impressed, and means for producing a capacitive reactance in the circuit of the other grid, which increases in value as the frequency of the oscillations impressed upon the circuit decreases.

In witness whereof I have hereunto set my hand this 23rd da of December, 1927.

BRO ER J. THOMPSON. 

